1. Field of the Invention
The invention relates generally to handheld electronic devices and, more particularly, to a handheld electronic device having a roller ball input.
2. Background of the Invention
Numerous types of handheld electronic devices are known. Examples of such handheld electronic devices include, for instance, personal data assistants (PDAs), handheld computers, two-way pagers, cellular telephones, and the like. Such handheld electronic devices are generally intended to be portable, and thus are relatively small. Many handheld electronic devices also features wireless communication capability, although many such handheld electronic devices are stand-alone devices that are functional without communication with other devices. With advances in technology, handheld electronic devices are being configured to include greater numbers of features while having relatively smaller form factors.
A user can interact or interface with a handheld electronic device in many fashions such as, for example, by actuating keys to provide inputs and by viewing outputs visually depicted on a display, as well as in numerous other fashions. It is desirable to configure a handheld electronic device to enable a user to provide inputs with minimal effort, because features that are complicated to use will simply be ignored by a user and left unused. Because of the generally competing considerations of reducing size of a handheld electronic device while increasing the complexity and versatility of the device, the various input devices on recent handheld electronic devices have often either been made relatively small or made to have multiple functions associated therewith, or both, and this can have the undesirable effect of complicating user inputs.
Efforts have been made to reduce the size of handheld electronic devices while maintaining or increasing their versatility by providing relatively fewer input members such as keys and by assigning multiple linguistic elements such as letters, strokes, ideograms, and the like, as well as digits, to at least some of the keys. Such a keyboard has been referred to as a reduced keyboard. Such handheld electronic devices will typically include a user interface having a routine that interprets the inputs from such input members. For instance, the user interface may provide for multitap input wherein a user actuates a key a number of times corresponding with the position of the desired linguistic element on a key. Another type of input routine is a disambiguation routine that performs a disambiguation function. That is, in response to an actuation of a key having multiple linguistic elements assigned thereto, the disambiguation routine outputs a linguistic element that is assumed to have been intended by the user based on various prediction models. Such a disambiguation routine typically will also output alternative linguistic elements or other types of alternative outputs intended to facilitate user input. Disambiguation systems have not, however, been without limitation.
As a user actuates keys to enter a word on a reduced keyboard, the quantity of possible letter permutations that could correspond with the series of keystrokes increases progressively and dramatically. A number of the letter permutations typically will be output to the user as variant proposed inputs. Numerous prediction models and other models and methodologies are employed to limit the quantity of variants that are displayed to the user in order to provide generally only those variants that a user would wish to view for purposes of possible selection by the user. The quantity of variants can, however, be quite large, and a user may need to pay significant attention to the displayed variants during text entry. Since handheld electronic devices having reduced keyboards are preferred to be easy to use, it would be desirable to configure a handheld electronic device having a reduced keyboard and a disambiguation routine in a fashion that reduces the amount of attention required of a user during text entry and during other use.
With increased complexity of applications available on handheld electronic devices, inputs from a user can similarly be required to be complex. Inputs that are provided by, for instance, buttons and joysticks, typically require multiple actuations to obtain multiple inputs, and such multiple actuations undesirably generally each require user attention. It is thus desirable to provide an improved input apparatus that provides greater versatility and that facilitates input into a handheld electronic device.